Between March 24 and April 1, the International Organization for Migration (IOM) conducted the second round of a rapid
representative assessment of the general population in Ukraine to gather insights into internal displacement and mobility flows, and to assess local needs. This general population survey serves as a preliminary source to identify areas with high humanitarian needs and to inform the targeting of response aiming to assist the war-affected population. The geographical scope of the assessment covers the entire territory of Ukraine, all five macro-regions (West, East, North, Centre, South, and the city of Kyiv), with the exception of the Crimean peninsula. 

This excellent report has a lot of data and charts to show the effects of the internal displacement. 

The full report can be found here